ROME , Italy -LRB- CNN -RRB- -- Officials monitoring the River Tiber in Rome fear it could break its banks as early as Friday evening after a spate of bad weather in Italy -- but do not expect major flooding .

A rescue boat patrols the swollen River Tiber in central Rome early Friday .

Guido Bertolaso , the head of the Italian Civil Protection Department said that there is a 20 to 30 percent chance the river could break its banks and cause disruption in some neighborhoods in northern Rome , but not in the historic city center .

Two people have died in weather-related incidents elsewhere in Italy .

`` We see that the flow is increasing , but it is not reaching a level that could be dangerous for the capital city of Italy , '' said Bertolaso about the Tiber , deeming the situation `` crucial but not serious . ''

Bertolaso , calling the situation `` quite extraordinary , '' labeled the flood threat and storms as the `` fifth most serious situation of the past 100 years . ''

`` But I think it is under control and the secret is to have the technology and the kind of organization to monitor the situation and to intervene if an emergency arises , '' he said . Bertolaso noted that authorities have been keeping a minute-by-minute watch because of heavy storms over the past few days .

He said the water level would probably increase for a few more hours and eventually peak between 8 p.m. and midnight local time Friday -LRB- between 1800 and 2200 GMT -RRB- .

`` If there will be no more rain , the situation is expected to stabilize , '' he said .

Rome Mayor Gianni Alemanno said he did not expect a major flood and noted that only a few dwellings have been evacuated -- primarily those inhabited by immigrants and Roma , who have set up makeshift camps on the banks of the Tiber .

`` I just recommend people to stay at home and not to rush to the river banks to watch the river swelling , '' Alemanno said .

Hundreds of volunteers and civil protection officials have been deployed around Rome to monitor the situation , the Civil Protection Department said .

Sandbags have been lined up to contain any possible river overflow , and the fire brigade is ready with amphibious vehicles .

Police have blocked access to some pedestrian bridges and river banks , while residents are being urged to use their vehicles only if necessary .

Firefighters Thursday had to rescue dozens of motorists stranded in their cars . Because of the intense rain , the streets of some northern Rome neighborhoods were already flooded by water and covered in thick brown mud .

One woman died near Rome early Thursday when her car was submerged by a wave of water and mud in an underpass . The body of a second victim was found in the southern region of Calabria after a bridge collapsed .

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NEW : Official : 20 - 30 percent chance that the River Tiber could overflow its banks

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Italy has been hit by a wave of bad weather that has claimed two lives

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One woman died near Rome when her car was submerged by a wave of water

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Body of a second victim was found in Calabria region after a bridge collapsed